if you use both a condom and birth control, do you have a 100 % chance of NOT being pregnant?

The condom is a kind of birth control. If you use it with another kind of birth control, you further reduce the risk of getting pregnant. But no method or combination of methods is guaranteed to be 100 percent effective. The only guaranteed way to not get pregnant is by not having vaginal intercourse. However, using both a condom and another method of birth control — like the pill, patch, ring, shot, implant, IUD, or pulling out — can make vaginal sex a lot safer. Using them together is an extremely effective way to reduce the risk of getting pregnant and of getting or spreading a sexually transmitted infection.